You can connect the device to the PC with a USB cable and access it via Explorer in the same way that you would a thumb drive. In addition, I like using Dropbox to sync files in a wireless fashion. I find this to be much easier and does not restrict movement of handset.

Via WLAN you can use a software that shares the Android file system via HTTP or FTP. For example if you use SwiFTP and change the shared folder from /sdcard to / you can access every file on the phone.

A connection via ADB is also possible in case you have a rooted phone - eg. via adb wireless.